I’ll list them from least complex and bare to most complex and descriptive, but all three are fairly short.
The church is that collection of people who are hearing the Word of God, responding to it with their lives, and who have obeyed Jesus’ specific commands to be baptized and proclaim his death in the Lord’s Supper.
Elsewhere Dever wrote (“The Church” in A Theology for the Church, 768):
The church is the body of people called by God’s grace through faith in Christ to glorify him by serving him in his world.
Me (PJ) (heavily dependent on believers.org quoted below):
The church is a group of Christians associated together under Christ to unite individuals to Christ and itself and to take responsibility for one another’s discipleship.
Update (2022): The church is a group of Christians collectively and personally responsible for one another’s discipleship in order to disciple their neighbors and their nations.
Update (2023): The church is a group of assembling Christians collectively responsible for one another’s (1) profession of and (2) continued commitment to trusting and following Jesus in order to disciple one another, their neighbors, and the nations.
The local church is a community of regenerated believers who confess Jesus Christ as Lord. In obedience to Scripture they organize under qualified leadership, gather regularly for preaching and worship, observe the biblical sacraments of baptism and communion, are unified by the Spirit, are disciplined for holiness, and scatter to fulfill the great commandment and the great commission as missionaries to the world for God’s glory and their joy.
Do you have any thoughts on this? I just reflected on the fact that the way you define church shapes the way you approach church planting.
Update:
The church is the gospel people who believe the gospel, who are a formed community around the gospel, and who demonstrate the gospel in everyday ways of life so that the world might know that the Father sent the Son.
Jeff Vanderstelt just posted another definition of the church with a good intro:
The Church is God’s People (who we are) saved by God’s Power (what He has done and is doing) for God’s Purposes (the good works he created us in Jesus Christ to do).
Art Azurdia:
A local church is a group of Christians who have intentionally united together for the expressed purpose of exercising New Testament Christianity to the glory of God and on behalf of one another in the world.
Believers.org defines a church like this:
A church is a group of believers in Jesus Christ, associated together, under Christ, for His purposes.
A local church is a group of Christians who regularly gather in Christ’s name to officially affirm and oversee one another’s membership in Jesus Christ and his kingdom through gospel preaching and gospel ordinances.
A local church is constituted by a group of Christians gathering together bearing Christ’s own authority to exercise the power of the keys of binding and loosing.
Or again: A local church is a group of Christians who regularly gather in Christ’s name to officially affirm and oversee one another’s membership in Jesus Christ and his kingdom through gospel preaching and gospel ordinances.